Category Archives: evolution

Aspergillus comparative transcriptional profiling

Researchers from Technical University of Denmark published some interesting results from comparing expression across the very distinct Aspergillus species.

Kudos also goes to making it Open Access. I am posting a few key figures below the fold because I can! They grew the fungi in bioreactors fermenting glucose or xylose. After calibrating the growth curves they were able to sample the appropriate time points for comparison of gene expression across these three species. They found a set of genes commonly expressed.

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Some links

I’ve been too busy to post much these last few days, but here are a few links to some papers I found interesting in my recent browsing.

Schmitt, I., Partida-Martinez, L.P., Winkler, R., Voigt, K., Einax, E., Dölz, F., Telle, S., Wöstemeyer, J., Hertweck, C. (2008). Evolution of host resistance in a toxin-producing bacterial–fungal alliance. The ISME Journal DOI: 10.1038/ismej.2008.19

LEVASSEUR, A. (2008). FOLy: an integrated database for the classification and functional annotation of fungal oxidoreductases potentially involved in the degradation of lignin and related aromatic compounds. Fungal Genetics and Biology DOI: 10.1016/j.fgb.2008.01.004

Shivaji, S., Bhadra, B., Rao, R.S., Pradhan, S. (2008). Rhodotorula himalayensis sp. nov., a novel psychrophilic yeast isolated from Roopkund Lake of the Himalayan mountain ranges, India. Extremophiles DOI: 10.1007/s00792-008-0144-z

Comparing development

PZ Meyers has a post summarizing of an older paper from Elliot Meyerowitz (2002) that comapares plant and animal development. In particular there is are some major themes summarized about how plants and animals form patterns and cell to cell signaling as part of development. What’s missing is what we’ve learned about within group comparisons where there are multiple lineages of single-celled and multicelled forms like choanozoa/metazoa (See M. brevicolis genome paper) and green algae (VolvoxChlamydomonas comparisons are forthcoming, but see Chlamydomonas genome paper).

I hope some of our work will provide more data to include in the comparison of fungal, animal, and plant development in the not too distant future.

Cryptococcus species deliniation What delineates species boundaries in fungi? Much work has been done on biological and phylogenetic species concepts in fungi. Some concepts are reviewed in Taylor et al 2006 and in Taylor et al 2000, and applications can be seen in several pathogens such as Paraccocidiodies, Coccidioides, and the model filamentous (non-pathogenic) fungus Neurospora.

A paper in Fungal Genetics and Biology on species definitions in Cryptococcus neoformans from multi-locus sequencing seeks to provide additional treatment of the observed diversity. A large study of 117 Cryptococcus isolates were examined through multi-locus sequencing (6 loci) and identified two monophyletic lineages within C. neoformans varieties that correspond to var. neoformans and var. grubii. However within the C. gattii samples they identified four monophyletic groups consistent with deep divergences observed from whole genome trees for two strains of C. gattii, MLST, and AFLP studies. By first defining species, we can now test whether any of the species groups have different traits including prevalence in clinical settings and in nature.

BOVERS, M., HAGEN, F., KURAMAE, E., BOEKHOUT, T. (2007). Six monophyletic lineages identified within Cryptococcus neoformans and Cryptococcus gattii by multi-locus sequence typing. Fungal Genetics and Biology DOI: 10.1016/j.fgb.2007.12.004

Phytopathogenic Fungi: what have we learned from genome sequences?

ResearchBlogging.orgA review in Plant Cell from Darren Soanes and colleagues summarizes some of the major findings about evolution of phytopathogenic fungi gleaned from genome sequencing highlighting 12 fungi and 2 oomycetes. By mapping evolution of genes identified as virulence factors as well as genes that appear to have similar patterns of diversification, we can hope to derive some principals about how phytopathogenic fungi have evolved from saprophyte ancestors.

They infer from phylogenies we’ve published (Fitzpatrick et al, James et al) that plant pathogenic capabilities have arisen at least 5 times in the fungi and at least 7 times in the eukaryotes. In addition they use data on gene duplication and loss in the ascomycete fungi (Wapinski et al) to infer there large numbers of losses and gains of genes have occurred in fungal lineages.

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Neurospora speciation through experimental evolution

ResearchBlogging.orgDettman, Anderson, and Kohn recently published a paper in BMC Evolutionary Biology on reproductive experimental evolution in two Neurospora crassa populations evolved under different selective conditions. This is a great study that complements work published last year in Nature on experimental evolution in Saccharomyces cerevisiae populations. Neurospora populations were evolved under high salt and low temperature and were started from either high diversity (interspecific crosses, N. crassa vs N. intermedia) or low diversity (intraspecific cross, two N. crassa isolates D143 (Louisiana, USA)and D69 (Ivory Coast)) as described in Figure 1. The experimentally evolved populations were then tested for asexual and sexual fitness (they were taken through complete meiotic cycle throughout the experiment to avoid insure there was selection on the sexual reproduction pathway.

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Sex in fungi: MAT locus cloned from a Zygomycete

On the cover of this week’s Nature is a picture of Phycomyces blakesleeanus Nature Coverhighlighting the discovery of the MAT locus in this Zygomycete fungus from Alex Idnurm and Joe Heitman and colleagues. While it was previously known that Zygomycetes (the Orange lineage represented by R. oryzae in the tree below) mate, the specific locus has until now, never been discovered. The authors in this study identified the MAT locus through a sequence search looking for HMG-box genes knowing that these are found the Mating Type locus in Basidiomycetes and Ascomycetes. They confirmed the identity through a through set of experiments that included PCR, sequencing and crosses of (+) and (-) strains of P. blakesleeanus, and Southern blots.

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Exploring CUG codon evolution in Candida

A recent PLoS One article “A Genetic Code Alteration Is a Phenotype Diversity Generator in the Human Pathogen Candida albicans” finds some pretty dramatic changes in gene expression and phenotypes by replacing the tRNAs for CUG back to Leucine (Leu; in the standard genetic code) from their meaning of Serine (Ser) in these Candida species. The CUG codon transition in some Candida spp has been of interest since it is an example of a recent change in the genetic code and provides a comparative system to study the mechanism and genome changes of how a genetic code shift is manifested.

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Yes, Ecology can improve Genomics

Blogging on Peer-Reviewed ResearchFew organisms are as well understood at the genetic level as Saccharomyces cerevisiae. Given that there are more yeast geneticists than yeast genes and exemplary resources for the community (largely a result of their size), this comes as no surprise. What is curious is the large number of yeast genes for which we’ve been unable to characterize. Of the ~6000 genes currently identified in the yeast genome, 1253 have no verified function (for the uninclined, this is roughly 21% of the yeast proteome). Egads! If we can’t figure this out in yeast, what hope do we have in non-model organisms?Lourdes Peña-Castillo and Timothy R. Hughes discuss this curious observation and its cause in their report in Genetics.

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